This invention relates to a new class of zwitterionic surfactant and more particularly to zwitterionic silicone surfactant compounds and their use as foam boosters for low sudsing household detergents.
Foaming power has become associated in consumer minds with high detersive power, however, foam has little direct influence in washing clothes, has no direct relationship to detergency in fabric washing, and does not improve cleaning in a laundry or home washing machine. In fact, in machine laundering operations, too much foam is undesirable because of interference with the mechanical action necessary for effective cleaning. In any event, compounds known as profoamers, foam boosters, and foam regulators, have been included in certain detergent products where high foam volume is functionally or aesthetically desirable. Typical foam boosters are amine oxides and alkanolamides, for example. In alkaline detergent solutions, semipolar amine oxide type nonionic surfactants generate copious suds, but high water solubility and a hygroscopic nature limit the use of amine oxides to liquid detergents. The use of fatty amine oxides in detergents is taught, for example, in U.S. Pat. No. 2,999,068, issued Sept. 5, 1961; U.S. Pat. No. 3,001,945, issued Sept. 26, 1961; U.S. Pat. No. 3,085,982, issued Apr. 16, 1963; U.S. Pat. No. 3,387,430: and U.S. Pat. No. 3,943,234, issued Mar. 9, 1976. In such detergent systems, it is not uncommon to include high levels of cationic and nonionic surfactant materials in order to improve the detergency and fabric softening properties of the system. However, these materials, especially the fabric softeners, often inhibit the potent foaming action of organic sulfonate surfactants present in the detergent such as linear alkylbenzene sulfonate, and hence neutralize their effectiveness. The result is a low sudsing detergent, and in such low sudsing detergents there is a need for an effective foam booster to be used in place of or in addition to the foam boosters present therein. Consumers have, in an effort to compensate for the low sudsing characteristics of such products, doubled and even tripled the dosage levels of detergent required in an effort to produce aesthetic foam, but the large dosages are ineffective and do not produce foam to any extent to the consternation of the consumer. Amine oxides have been employed in such highly formulated systems but such amine oxides tend to form toxic nitrosamines due to thermal decomposition. This disadvantage, along with the high water solubility and hygroscopicity of amine oxides, has created a need for an alternative profoamer. In U.S. Pat. No. 3,280,179, issued Oct. 18, 1966, there is disclosed zwitterionic organosulfobetaine surfactant compositions which are used to increase the foam height and improve the frothing action of organic anionic surfactants such as aqueous solutions of sodium lauryl sulfate. However, the foam boosters in U.S. Pat. No. 3,280,179, are not silicones as are the profoamers of the present invention nor are they comparable to the particular new class of zwitterionic siloxane based surfactant compositions of the present invention. For example, it is notoriously well known that silicones reduce foam rather than boost foam, and therefore there is disclosed herein a radically different and new catergory of silicone materials which function in a fashion which is traditionally and totally unexpected for such silicone materials. The silicones of the present invention also lower the surface tension of fluids ten to fifteen dynes per centimeter below that of the organic type surfactant as in U.S. Pat. No. 3,280,179, a factor which improves the overall foam boosting capacity and capabilities of the silicone type surfactant over that of the organic surfactant type. This additional advantage in a better lowering of the surface tension is also believed to result in improved cleaning or detergency in comparison to the cleaning or detergency that is obtained with organic type surfactants as represented, for example, by the foregoing prior art patent. Hence, the advantages of the present invention over that of the prior art, and the disadvantages of the prior art should be apparent, and the compounds of the present invention provide a viable and effective non-toxic alternative to the amine oxide compositions of the prior art.